Re-adding initial krait retention.

msm: pm: Support for Krait Retention
Introduce a new low power state for Krait, retention.
This state will lower the voltage to the Krait core to
retention voltage in addition to clock gating. This state
will be in between WFI and Standalone power collapse in
terms of time overhead and power savings.

Change-Id: I6b1f0a0d2e4954a705a047fd4a07f4dd1fb3518a
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>
(cherry picked from commit d27ca4a)

Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
(cherry picked from commit 3af7249)

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>

This reverts commit 07b2b5124473490141538206330b08109b9997f2.
Merge "Re-adding initial krait retention." into jb4.2